Deep
Vein Thrombosis and Travel

Deep Vein Thrombosis (DVT) is a
condition in which a clot, or thrombus, typically forms in a deep vein in a leg.
People with a DVT may notice pain and swelling in the leg where the clot has
formed, though smaller clots may not cause any symptoms. The major problem
occurs when a part of the clot breaks off and flows to the lungs. This
condition, called a Pulmonary Embolus (PE), can cause severe injury or death.
DVT's are known to occur in about 1 out of 1,000 people in the general population
from all causes.

Traveler’s Thrombosis

The condition has been erroneously
dubbed Economy Class Syndrome by some people because of the perception
that passengers in the more restrictive coach or economy class of the aircraft
are more likely to develop DVT's. Recent research, however, has found that
passengers in any seating class of the aircraft may develop a DVT. Research
indicates that any situation where one’s activity is limited for long periods—a
long automobile drive or train ride, for instance—may contribute to a DVT. For
this reason, the term Traveler’s Thrombosis is more appropriate.

Cause

The precise cause of Traveler’s
Thrombosis, while currently not clear, appears to be related, in part, to long
periods of sitting and inactivity. The decrease in activity may lead to
inadequate circulation of the blood in the legs. In addition, the veins may be
slightly constricted, which could also impair circulation in the legs. Other
conditions that alter blood flow or normal clotting mechanisms may make some
people more likely to develop a deep vein thrombosis (DVT). Some of these risk
factors include a prior DVT, certain heart diseases, cancer, pregnancy, smoking,
older age, and some blood clotting disorders. Recent major surgery or trauma is
also a risk factor. Certain medications may also contribute to formation of the
thrombus. Birth control pills and related hormones have been found to make some
people slightly more susceptible to forming DVT's.

Symptoms

Not all
DVT's cause noticeable symptoms, but the most common are swelling and redness in
the affected leg, often associated with some pain in the same area. Severe chest
pain or problems breathing may indicate a pulmonary embolus and should be
evaluated immediately.

Treatment

If
you suspect that you may have developed a DVT, you should immediately contact
your physician or go to an emergency room. Be sure to mention that you have
recently completed a long journey, as that information may aid in making the
correct diagnosis. Different procedures will be used to check for the presence
of a DVT and to evaluate a possible pulmonary embolus, if indicated. If a DVT or
PE is found, then you will usually be started on a blood thinner to help prevent
the clot from becoming larger while it slowly resolves.

Prevention

Since it has not been scientifically
established that there is a direct relationship between DVT and flying, there
may be no need for specific preventive methods. However, some practices may be
found to be beneficial:

Increasing leg muscle activity
during long periods of sitting improves blood flow in the legs. This may
include walking around the cabin or exercising your lower legs and ankles
while seated.

Drinking adequate fluids and
avoiding alcohol and caffeine may also help by preventing dehydration.

Loose-fitting clothing may be
beneficial in avoiding constriction of veins.

Some recommend taking short naps, instead of
long ones, to avoid prolonged inactivity.

If you
have any of the risk factors for DVT, consult your physician before long trips.
If indicated by a physician, special support socks or stockings can reduce blood
pooling in the legs and blood-thinning medications may be prescribed. For more
information, we encourage you to read “Traveler’s Thrombosis: A Review of Deep
Vein Thrombosis Associated With Travel,” published in Aviation, Space, and
Environmental Medicine, Vol. 72, No. 9, September 2001.

Summary

1. Deep Vein Thrombosis (DVT) is
a clot that forms in a leg vein.

2. A DVT can cause harm by
obstructing blood flow to a limb or if a part of the clot flows to the heart
or lungs.

3. A DVT can be caused by some
medical problems, medications, and long periods of inactivity.

4. The risk of developing a DVT
can be reduced by:

Occasional muscular activity

Maintaining hydration

Limiting alcohol and caffeine
intake

And, if indicated by a
physician:

Support socks or stockings

Blood thinning medications

Medical Facts
for Pilots Publication AM-400-03/2 was prepared by the FAA Aerospace Medical
Institute’s Aeromedical Education Division in Oklahoma City, OK. Check its web
site at
http://www.cami.jccbi.gov/aam-400A/400brochure.html for a list of
other pilot safety brochures. To order copies of this brochure, write to the
above address or call 405-954-4831.